Individuals in our society are required to make complex economic choices, often with uncertain outcomes, by integrating large amounts of information available to inform those choices. This daily requirement for decision making at all stages of life, together with increasing life spans and a growing accessibility to information among the youngest and eldest members of society, makes an evaluation of potential differences in decision making across age groups a critical area of research. Choosing advantageously among competing options with certain and uncertain outcomes is a product of individual subjective valuation of rewarding outcomes and the reinforcement learning processes required for accurately estimating those outcomes based on predictive information. Accordingly, a neuroeconomic framework of decision making under risk incorporating the contribution of age-related distinctions in subjective valuation and reinforcement learning provides a powerful tool for insight into the underlying substrates of choice behavior across the lifespan. The primary goal of the proposed work is to establish behavioral and neurobiological profiles of decision making under risk across the lifespan and examine the contribution of subjective reward valuation and reinforcement learning to these profiles at different life stages. We hypothesize that developmental/maturational changes in dopamine signaling from adolescence through adulthood and senescence is a fundamental contributor to choice behavior through the age-specific encoding of these essential components to the decision-making apparatus. We propose three specific aims examining dopamine signaling in the ventral striatum during probabilistic decision making, reinforcement learning, and subjective reward valuation in adolescent, adult, and aged rats.